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By Dan Moren

July 9, 2015 7:24 AM PT

Setting up your home Mac for remote file access

Working at home all the time can make even the hardiest soul a bit stir crazy, so I like to leave the house most days, just to mix it up a bit. However, that also means I frequently run into situations where I need to retrieve a file from my home iMac that I don’t have handy on my MacBook.

I keep most of my smaller files in Dropbox or iCloud Drive, but on occasion I need to grab something like, say, a podcast MP3. There are a number of ways to do this—configuring an SFTP server, for example, or using Back to My Mac1—but the one I’ve found most handy is using OS X’s built-in Screen Sharing.

Now, this does take a little preparation, but the good news it that once you invest the initial time to configure it, you shouldn’t need to do it again. Here are the key ingredients:

Local IPs: It’s generally easier if your home Mac (or Macs) always has the same IP on your local network. If you’re using an AirPort Extreme/Express or a Time Capsule, you can set this up using the DHCP Reservation option on the Network tab in AirPort Utility. Conveniently, that’s also the tab you’ll need to use for port forwarding.

Port forwarding: Because I’ve got multiple Macs on my local network, I need to specify a different external port for each computer that I connect to. The default port for screen sharing (or VNC, if you prefer) is 5900.2 Fortunately, there are plenty of unused ports nearby, so I just increment and use 5901, 5902, etc. Just forward a different one to port 5900 of the local IP of each of the Macs you want to connect to remotely. (The trick then is remembering which port goes to which Mac.)

Dynamic DNS: I wrote a piece years ago about setting up Dynamic DNS for your home machine.3 In simple terms, this lets you have a simple human-readable address to connect to instead of an IP address—rather than remembering 123.45.678.9, you use something like mymac.ddns.net. There are a number of options, but I recently switched to No-IP with solid results; it has a free option which only requires you to log in to its site once every 30 days or so to prevent your account from expiring.

This might all seem like a lot of work, but once you’ve done those above steps, you’re all set up. Now whenever you’re out and about all you have to do is hit Command-K in the Finder (or choose Go > Connect to Server…) and enter, for example, vnc://mymac.ddns.net:5901. (Set frequently used connections as favorites in the Connect to Server dialog box by clicking the + button.) OS X will automatically launch its Screen Sharing app and prompt you for the username and password for the Mac you’re connecting to (which you can, of course, save in the Keychain).

Once you’re looking at the screen of your remote computer, you can use it just as if you were sitting at it (albeit with some degree of lag, depending on your connection). But the best part is that you can also easily transfer files by simply dragging any file icon off the remote computer and onto your desktop.

And not only do you have remote access for the purpose of file transfers, but also for all of your screen-sharing needs. So if you need to do something on your home Mac while you’re out and about, the heavy lifting’s already done for you.